package org.bouncycastle.crypto;

/**
 * base interface that a public/private key block cipher needs to conform to.
 */
public interface AsymmetricBlockCipher {
    /**
     * initialise the cipher.
     * 
     * @param forEncryption
     *            if true the cipher is initialised for encryption, if false for
     *            decryption.
     * @param param
     *            the key and other data required by the cipher.
     */
    public void init(boolean forEncryption, CipherParameters param);

    /**
     * returns the largest size an input block can be.
     * 
     * @return maximum size for an input block.
     */
    public int getInputBlockSize();

    /**
     * returns the maximum size of the block produced by this cipher.
     * 
     * @return maximum size of the output block produced by the cipher.
     */
    public int getOutputBlockSize();

    /**
     * process the block of len bytes stored in in from offset inOff.
     * 
     * @param in
     *            the input data
     * @param inOff
     *            offset into the in array where the data starts
     * @param len
     *            the length of the block to be processed.
     * @return the resulting byte array of the encryption/decryption process.
     * @exception InvalidCipherTextException
     *                data decrypts improperly.
     * @exception DataLengthException
     *                the input data is too large for the cipher.
     */
    public byte[] processBlock(byte[] in, int inOff, int len)
            throws InvalidCipherTextException;
}
